Anti-corrosion compositions



United States Patent Ofihce 3,365,313 Patented Jan. 23, 1968 3,365,313ANTI-CORROSION COMPOSITIONS George Leathwhite Roberts, Jr., Lynchburg,Va., and

Robert Glenn Fessler, Martinsville, Bridgewater Township, SomersetCounty, N.J., assignors to American Cyanamid Company, Stamford, Conn, acorporation of Maine No Drawing. Original application June 11, 1962,Ser. No. 201,278. Divided and this application May 24, 1965, Ser. No.458,459

6 Claims. (Cl. 106-14) This application is a division of applicationSer. No. 201,278, filed June 11, 1962.

This invention relates to new insoluble organic quaternary ammoniumcomplexes, and to the provision of formulations of the same, suitablefor use in colorless or slightly colored anti-corrosion primer coatings.

The complexes of this invention are reaction products of water-solublenon-heterocyclic quaternary ammonium cationic surfactants (i.e., wettingagents) with heteropolyanionic acids. They are highly water insolublesubstances which, when applied to metal surfaces from suitableformulations, confer a high degree of corrosion resistance thereto. Thisproperty is rather surprising since it is virtually unprecedented toderive an insoluble anticorrosion coating from a chemical material whosemost characteristic property is water-solubility.

The possible fields of application of these compounds are manifold. Dueto their eventually colorless or pastel appearance, primer compositionsmay be formulated which may be overcoated with only one coat of even alight colored paint, in contrast to known primers comprising red lead,iron oxide, etc., which normally require multiple overcoats.

The soluble quaternary ammonium compounds useful for the preparation ofthe insoluble complexes of this invention are well-known in the field ofsurfactant chemistry. Being of the cationic type, they contain no acidicgroupings such as carboxyl and sulfonic acid moieties, although they maycontain basic groups such as amino radicals, or such common substituentssuch as hydroxyl and halogen radicals. The characteristic substituent onthe quaternary nitrogen is at least one higher alkyl group or one ormore polyoxyalkylene moieties. These, in turn, may be substituted byaryl or alkaryl groups to confer greater hydrophobicity, if desired, orhydrophilic groups such as hydroxyl radicals, if the opposite effect isdesired. While it is diificult to enumerate all the useful types ofcationic quaternary ammonium surfactants, since these compounds havediverse structures, a particularly useful class of quaternary compoundscan be represented by the following general formula:

wherein A* is a water solubilizing anion (e.g., chloride, bromide,perchlorate, etc.); R is lower alkyl (e.g., methyl, ethyl, propyl,butyl, amyl and hexyl); R is alkyl having 125 carbons (e.g., methyl,octyl, dodecyl, cetyl, cocyl,

lauryl, hexadecyl and octadecyl); R is either alkyl of more than sixcarbons, lower oxyalkylene having 1-10 oxyalkylene moieties andterminated by hydrogen, haloalkyl (e.g., fi-chloroethyl), amino-(loweralkyl), phenyl, alkylphenyl (e.g., tolyl, nonylphenyl nonytolyl andheptyl phenyl) and monocyclic ar(lower alkyl), e.g., benzyl; and R iseither alkyl of 1-6 carbons or R The heteropolyanionic acids which areemployed in forming the complexes of this invention, have beenpreviously described in the literature. An authoritative description isfound in Ephraim, Inorganic Chemistry, vol. I, 3rd ed., IntersciencePubl., pp. 495 et seq. (or pp. 512-524 of the 5th ed., 1948).

The chemistry of heteropolyanions is extremely complex. The term polyacid is applied to compounds which contain several acidic radicals. Whenthe acid contains only one kind of radical (H Cr O it is called anisopoly acid. If it contains more than one kind, the name heteropolyacid is applied. The acid anion is named a heteropolyanion. Onlyradicals of vanadic, tungstic and molybdic acids unite with radicals ofother fairly strong acids or with amphoteric metallic hydroxides to formheteropoly acids. The central radical can be any one of a number ofmetallic or non-metallic oxides (e.g., P 0 AS205, SiO TiO There appearsto be no real limit to the number of these compounds. In general, thecentral oxide is usually in the form of an octahedron and thisoctahedron is surrounded by any number of radicals from the vanadium,molybdenum or tungsten oxide. Due to their great molecular weight, thedetermination of structure of these compounds is extremely diflicult.

Examples of the inorganic heteropolyanionic acids which are used in thisinvention are: phosphomolybdic, phosphotungstic, titanomolybdic,arsenomolybdic, silicomolybdic, silicotungstic, silicotungstomolybdic,titanotungstic, phosphovanadic, titanovanadic, zirconomolybdic,zirconotungstic, zirconovanadic, boromolybdic, borotungstic,borovanadic, chromiomolybdic, chromiotungstic and chromiovanadic acids.Of these, the most preferred heteropolyanionic acids are thephosphomolybdic phosphotungstic (HqPW10035), silicomolybdic andsilicotungstic (H SiW O acids.

The complexes of this invention can be prepared by the method wherein awater-soluble salt is reacted with an acid to form a water-insolublesalt. Thus the acid from which the heteropolyanion is derived is firstprepared in aqueous solution by reaction of a metal oxide with awater-soluble alkali metal or ammonium vanadate, tungstate or molybdatesalt at a pH lower than 7 to form a solution of the acid correspondingto the inorganic heteropolyanion. The acid thus formed is then reactedwith a quaternary ammonium compound as above defined. The amount of thequaternary compound which is employed to form the complex, should besufiicient to provide three or more moles for each mole of theheteropolyanion. The complex, formed as a water-insoluble precipitate,is re moved by conventional methods such as filtration, and then washedand dried.

The primer compositions of which the above-described complexes are theactive anti-corrosion agents, may be of the conventional type. Normally,these contain three essential components and, optionally, additives toadapt them for special uses. The essential components are: (1) a resin,e.g., an alkyd modified linseed oil, a phenolic resin and a tung oilvarnish; (2) a solvent, e.g., xylene and methylisobutylketone; and (3)an anti-corrosion agent. If desired, additives may be incorporated intothe primer composition such as driers, wetting agents, dispersants, etc.In general, the anticorrosive agent comprises about 530 weight percentof the primer composition, but more or less may be employed to fitindividual requirements.

The present invention is further illustrated by the following examples,in which parts are by weight unless otherwise stated.

Example 1 Charge 28.0 parts of molybdic oxide to 1,000 parts of water at50 C. Add 15.6 parts of sodium hydroxide pellets. This dissolves themolybdic oxide in water. The resultant solution is heated to 80 C. andstirred at this temperature for five minutes. 3.3 parts of sodiumsilicate solution (28.0% SiO is dissolved in 100 parts of water. Thissodium silicate solution is added slowly to the sodium molybdatesolution. Then parts of concentrated HCl (36% real) is added dropwise tothe sodium l2-molybdosilicate solution at 80 C. This addition requiresabout five minutes. 34.1 parts of a solution of dodecyltrimethylammonium chloride in isopropanol was diluted with 100 parts ofhot water (50 C.). The dilute quaternary solution is added to thesilicomolybdic acid solution over a five-minute period. During addition,a pale yellow precipitate forms. The resultant suspension is stirred for15 minutes at 80 C., filtered, washed free of residual acid. and driedat C. The resultant powder is ground to less than 40 mesh. Elementalanalysis of this product indicates the following composition:

Actual: C, 26.62; H, 5.01; N, 3.13; Mo, 41.93; Si, 0.77; 0 (diff.),23.54. Theory: C, 26.40; H, 4.98; N, 2.10; Mo, 42.1; Si, 1.05; O(ditf.), 23.45.

Example 2 The procedure of Example 1 is repeated except that 18.45 partsof cetyl trimethylammonium chloride are used in place of the dodecylcompound. 48 parts of a pale yellow product are obtained.

Analysis indicates that the following compound was formed:

Example 3 A solution of silicomolybdic acid was prepared as inExample 1. 3.0 parts (12.5% real) by weight of a polymeric tertiaryamine acid salt sold under the trademark Acrysol-CA by the Rohm and HaasCorp. were dissolved in 100 parts of water. 2.5 parts of thesilicomolybdic acid solution was necessary to completely precipitate awhite product. This product was filtered, washed acid free and dried at60 C. 0.7 part of a pale white powder was obtained.

Example 4 3.0 parts by weight of a quaternary ammonium compound soldunder the trademark Acrysol-CQ by the Rohm and Haas Corp. (12.5% real)were dispersed in 100 parts of water. 2.5 parts of the silicomolybdicacid solution prepared as in Example 1 were required to completelyprecipitate this product. 0.7 part of a pale white powder was obtained.

4 Example 5 28 parts of molybdic oxide were added to 200 parts of water.15.6 parts of sodium hydroxide pellets were added to this molybdic oxidesuspension and the mixture stirred until a clear solution was obtained.13.3 parts of titanyl sulfate solution (9.7 grams TiO per ml. solution)were added to one liter of water. The pH of the titanyl sulfate solutionwas 2.25. 45 parts of concentrated HCl (36% real) were added to thetitanyl sulfate solution. The molybdate solution prepared above wasslowly added to the acid titanyl sulfate solution. The resultant pH was0.8 and this was adjusted to 5.6 by adding 20 parts sodium hydroxidepellets. 34.1 parts dodecyl trimethylammonium chloride (50% isopropanol)diluted with 200 ml. of water were added dropwise to the acidic12-molybdosilicate solution. A pale yellow precipitate formed. Theresultant suspension was filtered, Washed acid free, dried at 60 C. andground into a powder. 21.0 parts were formed. Analysis indicates thatthe following compound was formed.

Example 6 The procedure of Example 5 was repeated with the exceptionthat 6.1 parts of zirconyl sulfate (33.3% ZrO were substituted for thetitanyl sulfate solution. The pHs were identical except that theoriginal zirconyl sulfate solution had a pH of 1.8. 20.8 parts of awhite powder were formed. Analysis indicated that the following compoundwas formed.

The procedure of Example 1 was repeated except that 30.9 parts of aquaternary ammonium compound of the following structure were used:

27.8 parts of a pale yellow powder were obtained.

Example 9 The procedure of Example 1 was repeated except that 23.8 partsof the quaternary composition of the follow ing constitution were usedin place of the dodecyl trimethylammonium chloride:

I (3 5 cum-Q-oomomo onto rrtr -zorn]z CHa I i E I [Cpllm e -OC lIzCLlzOClInCl'Ig-N-C HaC 111N111] 26.6 parts of a pale yellow precipitatewere obtained.

Example The procedure of Example 1 was repeated with the followingammonium derivatives:

N0. Structure Parts by Yield Weight A RNC HgC HgCHgNHz C1 (R=8lkylOf1s-C1s) 17. 0

C H C H; C H;

Example 11 28 parts of molybdic oxide were suspended in 1,000 parts ofwater and 15.6 parts sodium hydroxide pellets were added. The resultingsuspension was heated to 55 C. until a solution was formed. Ice wasadded to cool the solution to C. (pH 6.29). parts concentrated HCl wasadded dropwies (pH 2.08). 8.65 parts CrCl -6H O was added to 200 partsof water and the resultant solution added to the solution of molybdicoxide (pH 2.02). 34 parts of dodecyl trimethylammonium chloride weredissolved in 200 parts of water and the resultant solution added to thesolution of chromimolybdate. A yellow green precipitate formed and wasstirred half an hour, filtered, washed acid free, dried and ground. 43.9parts of a yellow green powder were formed. Analysis indicated thefollowing compound was formed.

[ 12 25 3 a] s a 12 42 Example 12 The procedure of Example 11 wasfollowed except that the following metal salts were substituted for thechromium chloride.

100 parts of sodium tungstate dihydrate were dissolved in 300 partsboiling water. 1.55 parts boric acid were dissolved in 25 parts of waterat the boil. The boric acid was added to the sodium tungstate solutionand 75 parts of HCl (36%) were added dropwise to the boiling solution.The solution was cooled. 5.0 parts real of dodecyl trimethylammoniumchloride were added to 50 parts of water. The borotungstic solutionprepared above was added to the quaternary until precipitation wascomplete. The resultant suspension was filtered and the solid cake waswashed acid free, dried at 60 C. and ground. 5.8 parts of a white powderwere obtained.

[ 12 25 3 a] 6B2W12O42 Example 14 39.6 parts sodium tungstate dihydratewere dissolved in 300 ml. boiling water. 6.85 parts tit'anyl sulfatesolu- Example 13 was followed and 7.2 parts of a whi-tepowder wereobtained.

[ 12 25 3 a] 4 12 40 Example 1 5 The procedure of Example 14 wasfollowed except that 2.87 parts zirconyl sulfate were used in place ofthe titanyl sulfate solution. 10.2 parts of a white powder resulted.

Exwmple 16 The procedure of Example 15 was repeated except that aquaternary of the following formula marketed by Armour and Company asEthoquad-C12 was used in place of the amine used therein.

(CHzOHzOhH R=alkyl derived from coconut oil. x and y are small wholenumbers.

A white powder resulted.

Example 17 Silica extender (Asbestine 3X) 5.0

Soya oil modified alkyd resin-approximately 50% resin solids in mineralspirits 8.8

Mineral spirits 2.0

Xylene 6.25 The primer pigment used is either zinc chromate or a productof the preceding examples. The mixture described is placed in a ballmill containing 3 mm. glass beads. The mill is rolled for 24 hours. Thefinished paint is then poured or reduced to spray consistency andsprayed on iron panels. The film is allowed to air dry Ior half an hourand baked for 45 minutes at C.

In order to test the corrosion resistance of the film, a scratch is madein the center of the film with a sharp pointed instrument in order toexpose a thin portion of the iron panel. The panel is then immersed in awarm saturated salt solution for several days. The results for thefollowing Product of Immersion Medium Ratings Example No.

Poor.

Type.

M od.less

corrosion.

Sat. Saltdays 'Iype-The corrosion protection afforded with ZnCrO aconventional prime pigment, is herein used as the type standard" againstwhich the remaining pigments are compared.

2 Moddess corrosion-Less corrosion than noted in type st andard.

3 Equal-A rating of Equal" designates a. degree of corrosion protectionequal in magnitude to the type standard."

3. The composition of claim 1 wherein the quaternary ammonium moiety isa cationic surfactant of the following formula:

wherein A- is a water-solubilizing anion, R is lower alkyl, R is analkyl radical of from 1-25 carbons, R is selected from the groupconsisting of alkyl of more than 6 carbons and lower oxyalkyleneradicals having 110 re curring oxyalkylene moieties and terminated by amember selected from the group consisting of hydrogen, halogen, loweralkyl, amino, phenyl, alkylphenyl wherein any alkyl group has 1-9 carbonatoms and monocyclic ar(lower alkyl); and R is a member selected fromthe group consisting of alkyl of 1-6 carbons and R 4. The composition ofclaim 1 wherein the water-insoluble quaternary ammonium complex is adodecyl trimethyl ammonium salt of silicomolybdic acid.

5. The composition of claim 1 wherein the quaternary ammonium complex isa cetyl trimethyl ammonium salt of silicomolybdic acid.

6. The composition of claim 3 wherein the acid is a member selected fromthe group consisting of phosphomolybdic, phosphotungstic, silicomolybdicand silicotungstic acids.

References Cited UNITED STATES PATENTS 3,079,221 2/1963 Anderson 252390X 3,123,640 3/1964 Longley 260567.6 3,150,086 9/1964 Marsh et a1. 25239OX 3,201,467 8/1965 Oakes 252-390 X 3,254,102 5/1966 Swanson 260-429ALEXANDER H. BRODMERKEL, Primary Examiner.

L. HAYES, Assistant Examiner.

1. AS A NEW COMPOSITION OF MATTER AN ANTI-CORROSION PRIMER COATINGCOMPOSITION COMPRISING A RESIN, AND AN ORGANIC SOLVENT VEHICLE AND ANEFFECTIVE AMOUNT OF AN INSOLUBLE ORGANIC QUATERNARY AMMONIUM COMPLEXWHEREIN THE AMMONIUM MOIETY IS THE CATION OF A WATER-SOLUBLENON-HETEROCYCLIC QUATERNARY AMMONIUM CATIONIC SURFACTANT; AND THE ANIONIS DERIVED FROM A HETEROPOLYANIONIC ACID.